Main influencing factors and research progress of zinc oxide desulfurization performance at room temperature

H₂S is a colorless and highly toxic gas with rotten eggs-like odor, which widely presents in coal derived gas, biogas, natural gas and other industrial gases. Besides corroding pipelines and poisoning downstream catalysts, it can also endanger human health, even trace amounts of H₂S can cause people death. Moreover, when H₂S is released into the air, its oxidation product, sulfur dioxide, can cause acid rain, which can seriously harm forests and pollute groundwater. Therefore, in order to protect human health and ecological environment, maintain the operation of industrial production, H₂S in various industrial gases must be deeply removed. Zinc oxide has been widely used as polishing adsorbent in industrial process. In fact, zinc oxide shows favorable thermodynamics at room temperature, it is capable of reducing H₂S to less than 0.1 mg/m³ and well meet the strict requirements of various processes and environmental regulations on the concentration of H₂S in feed gas. However, limited by reaction kinetics, the desulfurization activity of zinc oxide at room temperature is very low. In order to improve the desulfurization activity of zinc oxide at room temperature, meeting the requirements of increasingly stringent environmental protection regulations and emerging technology such as proton exchange membrane fuel cells on H₂S content, this study provides a summary of the possible desulfurization mechanism during zinc oxide desulfurization process, highlighting the influence of key factors such as grain size and specific surface area, pore structure, lattice defects, heterostructure and relative humidity on the desulfurization performance. The recent advance of supported and porous nano zinc oxide desulfurizer is discussed. Furthermore, the analysis of the regeneration status of spent desulfurizer is presented. This review aims to offer valuable insights for the optimal design of desulfurizer.